1. Field of the Invention
The invention relates to an inductive non-contacting rotary joint particularly for computer tomographs, and also to a line arrangement for transmitting electrical energy from an inverter to a stationary coupler of the inductive rotary joint.
2. Description of the Relevant Art
A non-contacting inductive rotary joint for transmission of power in a computer tomograph is disclosed in U.S. Pat. No. 7,054,411 B2. An a.c. voltage in a range of typically 10 kHz to 100 Mhz is generated with a power inverter. This is fed into the primary winding of an inductive non-contacting rotary joint. This primary winding is connected to the stationary part of the gantry of the computer tomograph. Disposed to be movable relative to this is the secondary winding on the rotatable part of the gantry. It is magnetically coupled to the primary winding. The a.c. voltage transmitted to the secondary winding is rectified by means of a rectifier block and smoothed with capacitors connected to follow. This d.c. voltage then can be applied to effect supply to various electronic components. Furthermore, energy for feeding the X-ray tube is coupled out via a second secondary winding. For this, the a.c. voltage of the secondary winding of the rotary joint is fed into a high voltage transformer on the output side of which a cascade for generating a high voltage of an order of magnitude of 100 kV is disposed. This high voltage is used to supply the X-ray tube.
The amounts of power to be transmitted here are within a range of 10 kW to far beyond 100 kW. The power inverter for generating an a.c. voltage in this power class is usually installed in a location away from the gantry of the computer tomograph. Thus, the gantry in which a patient is examined can be designed to be as small and elegant as possible. In addition, cooling of the gantry is simplified because here it is not necessary also to lead away the power loss of the inverter. Problems are caused by the electrical connection between the inverter and the primary side of the inductive power transmitter. Thus, here the energy needed must be transmitted as a medium frequency signal via a cable having a length of several meters. In conventional cables high losses occur along the line, which on the one hand leads to a distinct reduction of the efficiency of the entire arrangement, and on the other hand to heating of the cable to an extent that it also needs to be cooled.